PLEASE EXPLAIN ALL OF THEM

The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30. Alice's, Betty's, and Carol's transactions run at about the same time. Which sums could be returned by Alice's transaction if all three transactions run under isolation level READ UNCOMMITTED, but not if they run under isolation level SERIALIZABLE? Identify one of those sums from the list below. a) 1040 b) 950 c) 1060 d) 1000 2. The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30. If Alice's, Betty's, and Carol's transactions run at about the same time, and each runs under isolation level READ COMITTED, which sums could be produced by Alice's transaction? Identify one of those sums from the list below. a) 990 b) 1080 c) 1040 d) 1050 2. The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20 , or 30 . Alice's, Betty's, and Carol's transactions run at about the same time. Which sums could be returned by Alice's transaction if all three transactions run under isolation level READ UNCOMMITTED, but not if they run under isolation level SERIALIZABLE? Identify one of those sums from the list below. a) 1010 b) 1020 c) 950 d) 1030 The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30. Alice's, Betty's, and Carol's transactions run at about the same time. Which sums could be returned by Alice's transaction if all three transactions run under isolation level READ UNCOMMITTED, but not if they run under isolation level SERIALIZABLE? Identify one of those sums from the list below. a) 1060 b) 950 c) 1040 d) 1010 The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30. If Alice's, Betty's, and Carol's transactions run at about the same time, and each runs under isolation level READ COMITTED, which sums could be produced by Alice's transaction? Identify one of those sums from the list below. a) 1040 b) 990 c) 950 d) 1020 The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECT SUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30. Alice's, Betty's, and Carol's transactions run at about the same time. Which sums could be returned by Alice's transaction if all three transactions run under isolation level READ UNCOMMITTED, but not if they run under isolation level SERIALIZABLE? Identify one of those sums from the list below. a) 1040 b) 1010 c) 950 d) 1020 The relation R(x) consists of a set of integers --- that is, one-component tuples with an integer component. Alice's transaction is a query: SELECTSUM(x) FROM R; COMMIT; Betty's transaction is a sequence of inserts: INSERT INTO R VALUES(10); INSERT INTO R VALUES(20); INSERT INTO R VALUES(30); COMMIT; Carol's transaction is a sequence of deletes: DELETE FROM R WHERE x=30; DELETE FROM R WHERE x=20; COMMIT; Before any of these transactions execute, the sum of the integers in R is 1000 , and none of these integers are 10,20, or 30 . Alice's, Betty's, and Carol's transactions run at about the same time. Which sums could be returned by Alice's transaction if all three transactions run under isolation level READ UNCOMMITTED, but not if they run under isolation level SERIALIZABLE? Identify one of those sums from the list below. a) 950 b) 1020 c) 1040 d) 1000